FIG. 11 shows a cross section figure of an example of conventional vertically aligned liquid crystal display. This liquid crystal display element comprises a liquid crystal cell 9, viewing angle compensation plates 3a and 3b provided on both sides of the liquid crystal cell 9, and polarizing plates 10 and 20 that sandwich the liquid crystal cell 9 and the viewing angle compensation plates 3a and 3b. The polarizing plates 10 and 20 are set up in a crossed Nicols arrangement. The liquid crystal cell 9 comprises a liquid crystal layer 30 with a negative dielectric constant anisotropy, Δε, and lower transparent substrates 4 and 5 that sandwich the liquid crystal layer 30. The upper and lower substrates 4 and 5 are provided with upper and lower transparent electrodes 11 and 15, respectively, and vertical alignment films 12 and 14 that are formed to cover the upper and lower electrodes 11 and 15 and are treated by alignment process, respectively.
A display area 18 is defined in a portion where the transparent electrodes 11 and 15 overlap each other, with the liquid crystal layer 30 sandwiched between them. In the zero of applied voltage, the liquid crystal molecules in the liquid crystal layer 30 are oriented nearly vertically to the transparent substrates 4 and 5, and the refractive index is nearly isotropic in in-plane directions to produce a dark state in the display area 18 when combined with the polarizing plates 10 and 20 in a crossed Nicols arrangement. When a voltage equal to or higher than the threshold voltage of the liquid crystal layer 30 is applied between the transparent electrodes 11 and 15, the liquid crystal molecules in the liquid crystal layer 30 are tilted to the transparent substrates 4 and 5, and the refractive index of liquid crystal layer 30 becomes anisotropic in in-plane, allowing the incident light to pass through the polarizing plates 10 and 20 in a crossed Nicols arrangement to produce a light state in the display area 18.
There are some different types of electrode arrangement used to drive liquid crystal display elements, such as segment electrode arrangement (including seven segment display and fixed pattern display) and simple matrix type dot matrix electrode. In the case of a segment electrode arrangement, a segment electrode to define display areas is formed on one of the transparent substrates, while a common electrode of a predefined shape to cover the display areas (or the segmented electrode) is formed on the other transparent substrate. In the case of a simple matrix type dot matrix electrode, characters and numbers are displayed by applying a voltage selectively to appropriate intersections (pixels) between the scanning electrodes formed on one transparent substrate and the signal electrodes formed on the other transparent substrate.
It is generally known that these liquid crystal display elements have good legibility when seen from the normal direction to the substrate, but the transmittance and color may change when seen from an oblique direction from the normal to the substrate.
Japanese Patent No. 2047880 discloses a liquid crystal display element comprising a viewing angle compensation plate having a negative uniaxial optical anisotropy (negative uniaxial film) or a viewing angle compensation plate having a negative biaxial optical anisotropy (negative biaxial film) provided between a polarizing plate and a substrate designed for conventional vertically aligned liquid crystal display elements.
Japanese Patents No. 3834304 and No. 2947350 disclose a multi-domain vertically aligned liquid crystal element in which the liquid crystal molecules constituting the liquid crystal layer are oriented in two or more directions.
Japanese Patent No. 2872628 and No. 4614200 disclose an alignment method to produce a nearly vertical alignment.